Karamaru Shuuai, Haramu Made Daku ~Kono Hatsujou wa Yokusei Dekinai~

There is still no 'suppressant' to subdue that rutting period. A dramatic omegaverse where instinct and pure love never stop! Mikoto Tachibana works hard for her younger brother's higher education after the death of her parents. She lives a peaceful life as a normal beta, but for some reason, she has a chance encounter with an alpha, Ritsu Yakumo, on the street, and for the first time, she goes into heat with him! 'Impossible, you say I'm in heat?　Ritsu is a super-elite among the Alphas, an Alpha who does not go into heat with Omegas. Although they have only just met, as soon as their hands touch, their bodies heat up and they kiss as their instincts demand. And then Mikoto is caressed deep inside with tongue and fingers...? Mikoto is awakened from Beta to Omega by Ritsu, and she becomes intensely and sweetly obsessed with him...